1. Field of the Invention
The present invention relates to the field of combustion equipment, and more particularly but not by way of limitation, to a burner assembly which substantially reduces the nitrogen oxide content of a combustion effluent from a boiler or the like.
2. Description of the Prior Art
Waste gases containing oxides of nitrogen are produced during the combustion of gaseous fuels. Tightening state and federal emission requirements have led to considerable efforts to find ways to remove or prevent the formation of nitrogen oxides in combustion processes so that such gases may be discharged to the atmosphere without a deleterious effect on the environment.
The majority of the prior art has been directed to the removal or the abatement of nitrogen oxides in the combustion of industrial waste gas streams so that stack gases can be discharged into the atmosphere without harm to the environment. For example, it has been proposed that nitrogen oxides be removed from waste streams with a medium capable of absorbing the nitrogen oxides. However, problems are encountered when using an absorption medium in that acidic liquids or other nitrogen containing noxious liquids may be formed which must be subjected to further treatment before they can be safely discharged into the environment.
Other prior art processes employed to remove or prevent formation of nitrogen oxides during combustion of industrial waste streams have utilized various types of catalysts or chemical compounds to selectively reduce the nitrogen oxides; or such processes have employed the concept of reducing the nitrogen oxides in the presence of excess hydrocarbon at elevated temperatures.
Much work has also been done in the modification of industrial burner assemblies. That is, the burner assemblies have been modified to accommodate staged fuel and/or staged air, as well as to employ recirculated flue gas as a coolant/diluent.
while many of the prior art systems have been successful in the reduction of nitrogen oxides during the combustion of industrial waste streams, such processes have generally been designed for large scale combustion operations and require expensive and complicated equipment, or extreme modification of existing equipment. That is, most of the attention has been directed to large scale combustion processes and equipment for industrial waste streams, while the problem of nitrogen oxide reduction in effluents from smaller scale equipment, such as boilers and the like, has not received as much attention. Thus, a need remains for economical combustion equipment and processes which employ modifications of existing combustion equipment for boilers and the like, which eliminate the deficiencies of the prior art burner assemblies, which operate safely and which are capable of reducing the amount of nitrogen oxides present in the combustion effluent produced by the operation of such burners.